This is a blog detailing the creation/evolution/ID controversy and assorted palaeontological news. I will post news here with running commentary.

Sunday, May 16, 2010

Douglas Theobald and Universal Common Ancestry

Douglas Theobald has written a technical paper on a test for universal common ancestry. The text of the paper is posted at Panda's Thumb, which also gives a short synopsis. Mike Steele and David Penny have also broken down the article here. They write:

So what is the signal in sequence data that provides the evidence for common ancestry? In essence, it is site-specific correlations in the amino acids between different species. These correlations fall off as the coalescence between lineages in a tree becomes deeper in the past, but if there are sufficient data, the correlations' cumulative significance becomes statistically strong. Conversely, if two lineages have completely separate origins, correlations between amino-acid site patterns in the corresponding two extant species vanish.

This article basically suggests, if I understand it correctly, that if species were independently created (think: *poof*), they would show smaller correlations in the coalescence results. This indicates that the further back you go, the sequence data shows common descent. As you go back in the fossil record and compare that to the genetic data of different species, certain protein sequences remain in common. Hat tip to Panda's Thumb.